Management of Acid Soils in Central Kenya Highlands

Abstract

The Ando-humic Nitisols within the highlands of central Kenya are characterized by low soil pH, low exchangeable bases and high percent Aluminium saturation resulting in low maize yields. An experiment was conducted to determine the effect of NP fertilizers (0 or 50 kg N & P205/ha), K (0 or 50 kg K20/ha), agricul turallime (L) at 0 or 1.0 t/ha and farmyard manure (FYM) at 0 or 5.0 t/ ha on maize yield and soil chemical characteristics over a period of eight years. The treatments were arranged in a Randomised Complete Block Design replicated two times. There was no significant increase in maize yield due to K application. Lime increased the maize grain yield by 156 % whereas the application of either FYM or NP fertilizer resulted in similar increases in maize grain yield (90 %). The highest maize grain yield of 4.5 t/ha was obtained by a combination of NP, lime and FYM. The highest (1.4 %) loss in organic C of was observed in plots that had not received any NP fertilizer and FYM. Agricultural lime increased the soil pH from 4.4 to above 5.5 irrespective of the NP or FYM treatments. Aluminium saturation decreased to zero in the plots that had received lime. There was a large increase in soil exchangeable Ca when lime was applied.